An interesting question was posted on another forum:
"can you get (ceramic) SMD caps (1206,0805 etc) with the values printed on
them?".

My first response was that I've very rarely seen this (like maybe once), and
while it is possible (see
http://www.synrad.com/search_apps/application_briefs/117-2.htm ), you
basically can't get labeled ones, they are almost always without markings.

It got me to thinking, why is it so?
My guess would be that it's due to the surface finish (or lack thereof) on
ceramic capacitors, and/or the delicate nature of their multi-layer
construction means they could be more easily damaged or properties altered
by the process.
As opposed to most SMD resistors that have a coating on them which would
allow for easy and accurate printing using various technologies.

Ahh..the caps could likewise be coated (and AFAIK they .are. coated
prior to potting for leaded versions).
Then, given that coating, they could be marked like the resistors you
mentioned.
BUT..that was "never" done so it will not be done (gotta stay in that
rut...).

I doult very much any manufacter would coat SMD caps as it would increase
the height to capacitor sits above the board, increasing the mounted
inductance, a crital factor when designing high frequecny boards.
Manufactuers spend a lot of money trying to reduce this unwanted property.

see http://www.avx.co.il/docs/techinfo/licadesign.pdf
or
http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedbackFAQ/D1A54E16FEC61B058525721E006EF53C /$file/Sun%20Paper%20on%20ESL%20&%20ESR.pdf
although these articles deal with via placement they discuss the need to
reduce the size of the loop that current flows in, a loop that would be
increased if a capacitor had an extra coating on it.

http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedbackFAQ/D1A54E16FEC61B058525721E006EF53C /$file/Sun%20Paper%20on%20ESL%20&%20ESR.pdf
It might be possible but I can't think of any non-conductive material that
could be layered thin enough and still go through a wave solder machine.

I didn't think an ink would withstand the the temperature (thinking
along the lines of markings either being etchings or printed then
encapsulated) but I have found an ink that could withstand the temperature,
can even be used on ceramic materials, only problem is it has the be air
brush stenciled, manufacture states it's not suitable for stamp or roller
application.
Okay so I've got no idea why such an ink isn't used to directly print to
the capacitor,

No, the original person who asked the question specifically stated sizes as
big as 1206.
So it has nothing to do with physical size.
Can't say I've seen the values ever printed on caps even larger than 1206.

The question is about whay it's common to mark SMD resistors, but not common
to mark SMD caps.

Originally, SMD parts were used along with thru hole. The "solder
side", as it was called, had thermal cure glue at all the SMD locations,
and the SMD parts get placed with no solder paste at all, and then the
curing oven bakes them in place. Then the boards went to a push line or
auto-inserter and the thru hole parts get added, being careful with the
solder side attached-but-not-yet-soldered parts. During wave solder, the
PCB gets passed over a flux bubbler. Next thing you know, the thru hole
and the bottom side SMD parts are soldered.

Bullshit, if you believe the jerks in this NG your business won't go very
far. If the part is too small to label, then how can you label it? That's
the real reason. It's not because of it's too cheap. Another wrong
interpretation of the Rednecks.